U.S. patent application number 17/057040 was filed with the patent office on 2021-07-08 for compound having triarylamine structure and organic electroluminescence device.
This patent application is currently assigned to HODOGAYA CHEMICAL CO., LTD.. The applicant listed for this patent is HODOGAYA CHEMICAL CO., LTD.. Invention is credited to Yuta HIRAYAMA, Kouki KASE, Kyung-Hwa PARK, Takuya UEHARA.
Application Number | 20210210693 17/057040 |
Document ID | / |
Family ID | 1000005509189 |
Filed Date | 2021-07-08 |
United States Patent
Application |
20210210693 |
Kind Code |
A1 |
UEHARA; Takuya ; et
al. |
July 8, 2021 |
COMPOUND HAVING TRIARYLAMINE STRUCTURE AND ORGANIC
ELECTROLUMINESCENCE DEVICE
Abstract
An object of the present invention is to provide an organic
compound that has excellent properties, with excellent hole
injection and transport performance, electron blocking capability,
and high stability in a thin film state, and furthermore to provide
a highly efficient and highly durable organic EL device by using
this compound. The present invention relates to a compound having a
triarylamine structure and being represented by the structural
formula (A-1) below, where A, B, and C may be the same or
different, and each represent a group represented by the structural
formula (B-1) below, a substituted or unsubstituted aromatic
hydrocarbon group, a substituted or unsubstituted aromatic
heterocyclic group, or a substituted or unsubstituted fused
polycyclic aromatic group, where at least one of A, B, and C is not
the group represented by the structural formula (B-1) below. (For
the symbols and the like in the formulae, see the descriptions in
the specification.)
Inventors: |
UEHARA; Takuya; (Tokyo,
JP) ; KASE; Kouki; (Tokyo, JP) ; PARK;
Kyung-Hwa; (Tokyo, JP) ; HIRAYAMA; Yuta;
(Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HODOGAYA CHEMICAL CO., LTD. |
Tokyo |
|
JP |
|
|
Assignee: |
HODOGAYA CHEMICAL CO., LTD.
Tokyo
JP
|
Family ID: |
1000005509189 |
Appl. No.: |
17/057040 |
Filed: |
June 20, 2019 |
PCT Filed: |
June 20, 2019 |
PCT NO: |
PCT/JP2019/024590 |
371 Date: |
November 19, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C07C 211/58 20130101;
H01L 51/5096 20130101; H01L 51/0059 20130101; H01L 51/5012
20130101; H01L 51/006 20130101; C07C 211/61 20130101; H01L 51/5088
20130101; H01L 51/5056 20130101; C07C 211/54 20130101 |
International
Class: |
H01L 51/00 20060101
H01L051/00; C07C 211/54 20060101 C07C211/54; C07C 211/61 20060101
C07C211/61; C07C 211/58 20060101 C07C211/58 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 25, 2018 |
JP |
2018-120071 |
Claims
1. A compound having a triarylamine structure and being represented
by the structural formula (A-1) below: ##STR00055## where A, B, and
C may be the same or different, and each represent a group
represented by the structural formula (B-1) below, a substituted or
unsubstituted aromatic hydrocarbon group, a substituted or
unsubstituted aromatic heterocyclic group, or a substituted or
unsubstituted fused polycyclic aromatic group, where at least one
of A, B, and C is not the group represented by the structural
formula (B-1) below: ##STR00056## where the dashed line portion
represents a binding site; R represents a hydrogen atom, a heavy
hydrogen atom, a fluorine atom, a chlorine atom, a cyano group, a
nitro group, a linear or branched alkyl group having 1 to 6 carbon
atoms and optionally having a substituent, a cycloalkyl group
having 5 to 10 carbon atoms and optionally having a substituent, a
linear or branched alkenyl group having 2 to 6 carbon atoms and
optionally having a substituent, a linear or branched alkyloxy
group having 1 to 6 carbon atoms and optionally having a
substituent, a cycloalkyloxy group having 5 to 10 carbon atoms and
optionally having a substituent, a substituted or unsubstituted
aromatic heterocyclic group, a substituted or unsubstituted
aromatic hydrocarbon group, a substituted or unsubstituted fused
polycyclic aromatic group, or a substituted or unsubstituted
aryloxy group; n is the number of Rs and represents an integer of 0
to 3, where, when n is 2 or 3, the plurality of Rs bonded to the
same benzene ring may be the same or different and may be bonded to
each other to form a ring via a single bond, a substituted or
unsubstituted methylene group, an oxygen atom, or a sulfur atom; L
represents a substituted or unsubstituted aromatic hydrocarbon
group, a substituted or unsubstituted aromatic heterocyclic group,
or a substituted or unsubstituted fused polycyclic aromatic group;
m represents an integer of 1 to 3, where, when m is 2 or 3, Ls may
be the same or different; and Ar.sub.1 and Ar.sub.2 may be the same
or different, and each represent a substituted or unsubstituted
aromatic hydrocarbon group, a substituted or unsubstituted aromatic
heterocyclic group, or a substituted or unsubstituted fused
polycyclic aromatic group.
2. The compound having a triarylamine structure according to claim
1, wherein the group represented by the structural formula (B-1) is
a group represented by the structural formula (B-2) below:
##STR00057## where Ar.sub.1, Ar.sub.2, L, m, n, and R are as
defined in the structural formula (B-1).
3. The compound having a triarylamine structure according to claim
2, wherein L in the group represented by the structural formula
(B-2) is an unsubstituted aromatic hydrocarbon group, an
unsubstituted aromatic heterocyclic group, or an unsubstituted
fused polycyclic aromatic group.
4. The compound having a triarylamine structure according to claim
3, wherein the group represented by the structural formula (B-2) is
a group represented by the structural formula (B-3) below:
##STR00058## where Ar.sub.1, Ar.sub.2, n, and R are as defined in
the structural formula (B-1).
5. The compound having a triarylamine structure according to claim
3, wherein the group represented by the structural formula (B-2) is
a group represented by the structural formula (B-4) below:
##STR00059## where Ar.sub.1, Ar.sub.2, n, and R are as defined in
the structural formula (B-1).
6. The compound having a triarylamine structure according to claim
5, wherein the group represented by the structural formula (B-4) is
a group represented by, the structural formula (B-5) below:
##STR00060## where Ar.sub.1, Ar.sub.2, n, and R are as defined in
the structural formula (B-1).
7. The compound having a triarylamine structure according to claim
6, wherein n in the structural formula (B-5) is 0 or 1.
8. The compound having a triarylamine structure according to claim
6, wherein n in the structural formula (B-5) is 0.
9. The compound having a triarylamine structure according to claim
4, wherein the group represented by the structural formula (B-3) is
a group represented by the structural formula (B-6) below:
##STR00061## where Ar.sub.1, Ar.sub.2, n, and R are as defined in
the (B-1).
10. The compound having a triarylamine structure according to claim
9, wherein n in the structural formula (B-6) is 0 or 1.
11. The compound having a triarylamine structure according to claim
9, wherein n in the structural formula (B-6) is 0.
12. An organic EL device comprising a pair of electrodes and one or
more organic layers sandwiched therebetween, wherein the compound
having a triarylamine structure according to claim 1 is used as a
constituent material of at least one of the organic layers.
13. The organic EL device according to claim 12, wherein the at
least one organic layer is a hole transport layer.
14. The organic EL device according to claim 12, wherein the at
least one organic layer is an electron blocking laver.
15. The organic EL device according to claim 12, wherein the at
least one organic layer is a hole injection layer.
16. The organic EL device according to claim 12, wherein the at
least one organic layer is a light emitting layer.
Description
TECHNICAL FIELD
[0001] The present invention relates to a compound that is suitable
for organic electroluminescence devices (hereinafter referred to
simply as "organic EL devices"), which are self-light-emitting
devices favorably used in various display apparatuses, and more
particularly relates to a compound having a triarylamine structure
and an organic EL device in which the compound is used.
BACKGROUND ART
[0002] Since organic EL devices are self-emissive devices, they are
brighter than liquid crystal devices, have superior display
viewability, and can provide a clearer display. For these reasons,
active studies have been carried out on organic EL devices.
[0003] In 1987, C. W. Tang et al. of Eastman Kodak Company made a
practical organic EL device in which an organic material was used,
by developing a device having a stacked layer structure in which
various functions were assigned to different materials. They
achieved a high luminance of 1,000 cd/m.sup.2 or higher at a
voltage of 10 V or less by stacking a layer of a fluorescent body
capable of transporting electrons and a layer of an organic
substance capable of transporting holes, injecting both charges
into the fluorescent body layer, and thereby causing the layer to
emit light (see Patent Literatures 1 and 2, for example).
[0004] Many improvements have been heretofore made to organic EL
devices to put them to practical use. High efficiency and
durability have been achieved by subdividing the functions assigned
to respective layers of the stacked layer structure and forming an
electroluminescence device in which an anode, a hole injection
layer, a hole transport layer, a light emitting layer, an electron
transport layer, an electron injection layer, and a cathode are
sequentially provided on a substrate (see Non-Patent Literature 1,
for example).
[0005] To further increase light emission efficiency, attempts have
been made to utilize triplet excitons, and the utilization of
phosphorescent light emitting compounds has been investigated (see
Non-Patent Literature 2, for example).
[0006] Moreover, devices that utilize light emission based on
thermally activated delayed fluorescence (TADF) have also been
developed. In 2011, Adachi et al. from Kyushu University realized
an external quantum efficiency of 5.3% with a device that uses a
thermally activated delayed fluorescence material (see Non-Patent
Literature 3, for example).
[0007] The light emitting layer can also be prepared by doping a
charge transporting compound, generally called a host material,
with a fluorescent compound, a phosphorescent light emitting
compound, or a material that radiates delayed fluorescence. As
stated in the non-patent literature above, the selection of the
organic materials in an organic EL device greatly affects the
characteristics of that device, such as efficiency and durability
(see Non-Patent Literature 2, for example).
[0008] In an organic EL device, the charges injected from both
electrodes recombine in the light emitting layer, thereby producing
light emission, and how efficiently the charges of both the holes
and the electrons are passed on to the light emitting layer is of
importance. Therefore, a device that exhibits excellent carrier
balance is required. Also, by improving electron blockability, that
is, the ability to block electrons injected from the cathode, the
probability of holes and electrons recombining is increased, and
even higher light emission efficiency can be achieved. Therefore,
the functions to be fulfilled by the hole transport material are
important, and a hole transport material having high hole
injectability, high hole mobility, high electron blockability, and
high durability against electrons has been in demand.
[0009] Moreover, with regard to device lifespan, heat resistance
and amorphousness of the materials are also important. A material
with low heat resistance thermally decomposes due to heat produced
during device driving, even at low temperatures, and the material
deteriorates. A material with low amorphousness causes
crystallization of a thin film to occur even in a short period of
time, and the device deteriorates. Thus, high heat resistance and
good amorphousness are required of the materials to be used.
[0010] N,N'-diphenyl-N,N'-di(.alpha.-naphthyl)benzidine
(hereinafter abbreviated as NPD) and various aromatic amine
derivatives are known as hole transport materials that have been
heretofore used in organic EL devices (see Patent Literatures 1 and
2, for example). NPD has good hole transport capability, but the
glass transition point (Tg), which is an indicator of heat
resistance, is as low as 96.degree. C., and therefore, under
high-temperature conditions, the device characteristics degrade due
to crystallization.
[0011] Moreover, among the aromatic amine derivatives disclosed in
Patent Literatures 1 and 2, there are also compounds with an
excellent hole mobility of 10.sup.-3 cm.sup.2/Vs or higher, but the
electron blockability of these compounds is insufficient, which
allows some electrons to pass through the light emitting layer, and
therefore, there are problems in that, for example, no increase in
light emission efficiency can be expected. Thus, materials with
which thin films having higher electron blockability, higher
stability, and higher heat resistance can be obtained are needed to
further increase efficiency.
[0012] Furthermore, aromatic amine derivatives with high durability
have also been reported (see Patent Literature 3, for example).
However, these aromatic amine derivatives are used as charge
transport materials in electrophotographic photoreceptors, and
there are no examples of application to an organic EL device.
[0013] Arylamine compounds having a substituted carbazole structure
have been suggested as compounds with improved properties such as
heat resistance and hole injectability (see Patent Literatures 4
and 5, for example). However, even though heat resistance, light
emission efficiency, and the like of devices in which these
compounds are used for a hole injection layer or a hole transport
layer have been improved, the results are still insufficient.
Therefore, for a further decrease in driving voltage and a further
increase in light emission efficiency, there is demand for a hole
transport material having high hole injectability, high hole
mobility, high electron blockability, and, furthermore, high
durability against electrons.
CITATION LIST
Patent Literature
[0014] Patent Literature 1: U.S. Pat. No. 5,792,557 [0015] Patent
Literature 2: U.S. Pat. No. 5,639,914 [0016] Patent Literature 3:
U.S. Pat. No. 7,799,492 [0017] Patent Literature 4: U.S. Pat. No.
8,021,764 [0018] Patent Literature 5: EP 2684932
Non-Patent Literature
[0018] [0019] Non-Patent Literature 1: Proceedings of the 9th
Meeting of the Japan Society of Applied Physics, pp. 55-61 (2001)
[0020] Non-Patent Literature 2: Proceedings of the 9th Meeting of
the Japan Society of Applied Physics, pp. 23-31 (2001) [0021]
Non-Patent Literature 3: Appl. Phys. Let., 98, 083302 (2011)
SUMMARY OF INVENTION
[0022] An object of the present invention is to provide an organic
compound that has excellent properties, with excellent hole
injection and transport performance, electron blocking capability,
and high stability in a thin film state, as a material for a highly
efficient and highly durable organic EL device, and furthermore to
provide a highly efficient and highly durable organic EL device by
using this compound.
[0023] An organic compound to be provided by the present invention
should have the following physical properties: (1) good hole
injection properties, (2) high hole mobility, (3) excellent
electron blocking capability, (4) stability in a thin film state,
and (5) excellent heat resistance.
[0024] Moreover, an organic EL device to be provided by the present
invention should have the following physical characteristics: (1)
high light emission efficiency and high power efficiency, (2) a low
light-emission start voltage, (3) a low actual driving voltage, and
(4) a long lifespan.
[0025] To achieve the above-described object, the inventors of the
present invention conducted in-depth research, and found that a
triarylamine compound having a specific structure has excellent
hole injection and transport capabilities, as well as excellent
stability and durability of a thin film, and furthermore, also has
excellent electron blockability. Thus, the present invention was
accomplished.
[0026] That is, the present invention provides the followings:
[0027] 1) A compound having a triarylamine structure and being
represented by the structural formula (A-1) below:
##STR00001##
[0028] where A, B, and C may be the same or different, and each
represent a group represented by the structural formula (B-1)
below, a substituted or unsubstituted aromatic hydrocarbon group, a
substituted or unsubstituted aromatic heterocyclic group, or a
substituted or unsubstituted fused polycyclic aromatic group, where
at least one of A, B, and C is not the group represented by the
structural formula (B-1) below:
##STR00002##
[0029] where the dashed line portion represents a binding site;
[0030] R represents a hydrogen atom, a heavy hydrogen atom, a
fluorine atom, a chlorine atom, a cyano group, a nitro group, a
linear or branched alkyl group having 1 to 6 carbon atoms and
optionally having a substituent, a cycloalkyl group having 5 to 10
carbon atoms and optionally having a substituent, a linear or
branched alkenyl group having 2 to 6 carbon atoms and optionally
having a substituent, a linear or branched alkyloxy group having 1
to 6 carbon atoms and optionally having a substituent, a
cycloalkyloxy group having 5 to 10 carbon atoms and optionally
having a substituent, a substituted or unsubstituted aromatic
heterocyclic group, a substituted or unsubstituted aromatic
hydrocarbon group, a substituted or unsubstituted fused polycyclic
aromatic group, or a substituted or unsubstituted aryloxy group; n
is the number of Rs and represents an integer of 0 to 3, where,
when n is 2 or 3, the plurality of Rs bonded to the same benzene
ring may be the same or different and may be bonded to each other
to form a ring via a single bond, a substituted or unsubstituted
methylene group, an oxygen atom, or a sulfur atom;
[0031] L represents a substituted or unsubstituted aromatic
hydrocarbon group, a substituted or unsubstituted aromatic
heterocyclic group, or a substituted or unsubstituted fused
polycyclic aromatic group; m represents an integer of 1 to 3,
where, when m is 2 or 3, Ls may be the same or different; and
[0032] Ar.sub.1 and Ar.sub.2 may be the same or different, and each
represent a substituted or unsubstituted aromatic hydrocarbon
group, a substituted or unsubstituted aromatic heterocyclic group,
or a substituted or unsubstituted fused polycyclic aromatic
group.
[0033] 2) The compound having a triarylamine structure as set forth
in clause 1) above, wherein the group represented by the structural
formula (B-1) is a group represented by the structural formula
(B-2) below:
##STR00003##
[0034] where Ar.sub.1, Ar.sub.2, L, m, n, and R are as defined in
the structural formula (B-1).
[0035] 3) The compound having a triarylamine structure as set forth
in clause 2) above, wherein L in the group represented by the
structural formula (B-2) is an unsubstituted aromatic hydrocarbon
group, an unsubstituted aromatic heterocyclic group, or an
unsubstituted fused polycyclic aromatic group.
[0036] 4) The compound having a triarylamine structure as set forth
in clause 3) above, wherein the group represented by the structural
formula (B-2) is a group represented by the structural formula
(B-3) below:
##STR00004##
[0037] where Ar.sub.1, Ar.sub.2, n, and R are as defined in the
structural formula (B-1).
[0038] 5) The compound having a triarylamine structure as set forth
in clause 3) above, wherein the group represented by the structural
formula (B-2) is a group represented by the structural formula
(B-4) below:
##STR00005##
[0039] where Ar.sub.1, Ar.sub.2, n, and R are as defined in the
structural formula (B-1).
[0040] 6) The compound having a triarylamine structure as set forth
in clause 5) above, wherein the group represented by the structural
formula (B-4) is a group represented by the structural formula
(B-5) below:
##STR00006##
[0041] where Ar.sub.1, Ar.sub.2, n, and R are as defined in the
structural formula (B-1).
[0042] 7) The compound having a triarylamine structure as set forth
in clause 6) above, wherein n in the structural formula (B-5) is 0
or 1.
[0043] 8) The compound having a triarylamine structure as set forth
in clause 6) above, wherein n in the structural formula (B-5) is
0.
[0044] 9) The compound having a triarylamine structure as set forth
in clause 4) above, wherein the group represented by the structural
formula (B-3) is a group represented by the structural formula
(B-6) below:
##STR00007##
[0045] where Ar.sub.1, Ar.sub.2, n, and R are as defined in the
(B-1).
[0046] 10) The compound having a triarylamine structure as set
forth in clause 9) above, wherein n in the structural formula (B-6)
is 0 or 1.
[0047] 11) The compound having a triarylamine structure as set
forth in clause 9) above, wherein n in the structural formula (B-6)
is 0.
[0048] 12) An organic EL device including a pair of electrodes and
one or more organic layers sandwiched therebetween, wherein the
compound having a triarylamine structure as set forth in any one of
clauses 1) to 11) above is used as a constituent material of at
least one of the organic layers.
[0049] 13) The organic EL device as set forth in clause 12) above,
wherein the at least one organic layer is a hole transport
layer.
[0050] 14) The organic EL device as set forth in clause 12) above,
wherein the at least one organic layer is an electron blocking
layer.
[0051] 15) The organic EL device as set forth in clause 12) above,
wherein the at least one organic layer is a hole injection
layer.
[0052] 16) The organic EL device as set forth in clause 12) above,
wherein the at least one organic layer is a light emitting
layer.
[0053] Specific examples of the "aromatic hydrocarbon group", the
"aromatic heterocyclic group", or the "fused polycyclic aromatic
group" of the "substituted or unsubstituted aromatic hydrocarbon
group", the "substituted or unsubstituted aromatic heterocyclic
group", or the "substituted or unsubstituted fused polycyclic
aromatic group" represented by R in the structural formulae (B-1)
to (B-6) include a phenyl group, a biphenylyl group, a terphenylyl
group, a naphthyl group, an anthracenyl group, a phenanthrenyl
group, a fluorenyl group, a spirobifluorenyl group, an indenyl
group, a pyrenyl group, a perylenyl group, a fluoranthenyl group, a
triphenylenyl group, a pyridyl group, a pyrimidinyl group, a
triazinyl group, a furyl group, a pyrrolyl group, a thienyl group,
a quinolyl group, an isoquinolyl group, a benzofuranyl group, a
benzothienyl group, an indolyl group, a carbazolyl group, a
benzooxazolyl group, a benzothiazolyl group, a quinoxalinyl group,
a benzimidazolyl group, a pyrazolyl group, a dibenzofuranyl group,
a dibenzothienyl group, a naphthyridinyl group, a phenanthrolinyl
group, an acridinyl group, a carbolinyl group, and the like.
Furthermore, the group may also be selected from aryl groups having
6 to 30 carbon atoms and heteroaryl groups having 2 to 30 carbon
atoms. These substituents and the benzene rings substituted by the
substituents, as well as a plurality of substituents that
substitute the same benzene ring may be bonded to each other to
form a ring via a single bond, a substituted or unsubstituted
methylene group, a substituted or unsubstituted amino group, an
oxygen atom, or a sulfur atom.
[0054] Specific examples of the "linear or branched alkyl group
having 1 to 6 carbon atoms", the "cycloalkyl group having 5 to 10
carbon atoms", or the "linear or branched alkenyl group having 2 to
6 carbon atoms" of the "linear or branched alkyl group having 1 to
6 carbon atoms and optionally having a substituent", the
"cycloalkyl group having 5 to 10 carbon atoms and optionally having
a substituent", or the "linear or branched alkenyl group having 2
to 6 carbon atoms and optionally having a substituent" represented
by R in the structural formulae (B-1) to (B-6) include a methyl
group, an ethyl group, an n-propyl group, an isopropyl group, an
n-butyl group, an isobutyl group, a tert-butyl group, an n-pentyl
group, an isopentyl group, a neopentyl group, an n-hexyl group, a
cyclopentyl group, a cyclohexyl group, a 1-adamantyl group, a
2-adamantyl group, a vinyl group, an allyl group, an isopropenyl
group, a 2-butenyl group, and the like. These substituents and the
benzene rings substituted by the substituents, as well as a
plurality of substituents that substitute the same benzene ring may
be bonded to each other to form a ring via a single bond, a
substituted or unsubstituted methylene group, a substituted or
unsubstituted amino group, an oxygen atom, or a sulfur atom.
[0055] Specific examples of the "linear or branched alkyloxy group
having 1 to 6 carbon atoms" or the "cycloalkyloxy group having 5 to
10 carbon atoms" of the "linear or branched alkyloxy group having 1
to 6 carbon atoms and optionally having a substituent" or the
"cycloalkyloxy group having 5 to 10 carbon atoms and optionally
having a substituent" represented by R in the structural formulae
(B-1) to (B-6) include a methyloxy group, an ethyloxy group, an
n-propyloxy group, an isopropyloxy group, an n-butyloxy group, a
tert-butyloxy group, an n-pentyloxy group, an n-hexyloxy group, a
cyclopentyloxy group, a cyclohexyloxy group, a cycloheptyloxy
group, a cyclooctyloxy group, a 1-adamantyloxy group, a
2-adamantyloxy group, and the like. These substituents and the
benzene rings substituted by the substituents, as well as a
plurality of substituents that substitute the same benzene ring may
be bonded to each other to form a ring via a single bond, a
substituted or unsubstituted methylene group, a substituted or
unsubstituted amino group, an oxygen atom, or a sulfur atom.
[0056] Specific examples of the "substituent" of the "substituted
aromatic hydrocarbon group", the "substituted aromatic heterocyclic
group", the "substituted fused polycyclic aromatic group", the
"linear or branched alkyl group having 1 to 6 carbon atoms and
optionally having a substituent", the "cycloalkyl group having 5 to
10 carbon atoms and optionally having a substituent", the "linear
or branched alkenyl group having 2 to 6 carbon atoms and optionally
having a substituent", the "linear or branched alkyloxy group
having 1 to 6 carbon atoms and optionally having a substituent", or
the "cycloalkyloxy group having 5 to 10 carbon atoms and optionally
having a substituent" represented by R in the structural formulae
(B-1) to (B-6) include the following groups: a heavy hydrogen atom,
a cyano group, and a nitro group; halogen atoms such as a fluorine
atom, a chlorine atom, a bromine atom, and an iodine atom; silyl
groups such as a trimethylsilyl group and a triphenylsilyl group;
linear or branched alkyl groups having 1 to 6 carbon atoms such as
a methyl group, an ethyl group, and a propyl group; linear or
branched alkyloxy groups having 1 to 6 carbon atoms such as a
methyloxy group, an ethyloxy group, and a propyloxy group; alkenyl
groups such as a vinyl group and an allyl group; aryloxy groups
such as a phenyloxy group and a tolyloxy group; arylalkyloxy groups
such as a benzyloxy group and a phenethyloxy group; aromatic
hydrocarbon groups or fused polycyclic aromatic groups such as a
phenyl group, a biphenylyl group, a terphenylyl group, a naphthyl
group, an anthracenyl group, a phenanthrenyl group, a fluorenyl
group, a spirobifluorenyl group, an indenyl group, a pyrenyl group,
a perylenyl group, a fluoranthenyl group, and a triphenylenyl
group; and aromatic heterocyclic groups such as a pyridyl group, a
thienyl group, a furyl group, a pyrrolyl group, a quinolyl group,
an isoquinolyl group, a benzofuranyl group, a benzothienyl group,
an indolyl group, a carbazolyl group, a benzooxazolyl group, a
benzothiazolyl group, a quinoxalinyl group, a benzimidazolyl group,
a pyrazolyl group, a dibenzofuranyl group, a dibenzothienyl group,
and a carbolinyl group. These substituents may further be
substituted by any of the substituents listed above as examples.
Moreover, these substituents and the benzene rings substituted by
the substituents, as well as a plurality of substituents that
substitute the same benzene ring may be bonded to each other to
form a ring via a single bond, a substituted or unsubstituted
methylene group, a substituted or unsubstituted amino group, an
oxygen atom, or a sulfur atom.
[0057] Examples of the "aromatic hydrocarbon group", the "aromatic
heterocyclic group", or the "fused polycyclic aromatic group" of
the "substituted or unsubstituted aromatic hydrocarbon group", the
"substituted or unsubstituted aromatic heterocyclic group", or the
"substituted or unsubstituted fused polycyclic aromatic group"
represented by Ar.sub.1 and Ar.sub.2 in the structural formulae
(B-1) to (B-6) are similar to those listed above as examples with
respect to the "aromatic hydrocarbon group", the "aromatic
heterocyclic group", or the "fused polycyclic aromatic group"
represented by R in the structural formulae (B-1) to (B-5). The
same holds true for the forms that the group can take.
[0058] Examples of the "substituent" of the "substituted aromatic
hydrocarbon group", the "substituted aromatic heterocyclic group",
or the "substituted fused polycyclic aromatic group" represented by
Ar.sub.1 and Ar.sub.2 in the structural formulae (B-1) to (B-6) are
similar to those listed above as examples with respect to the
"substituent" of those represented by R in the structural formulae
(B-1) to (B-5). The same holds true for the forms that the
substituent can take.
[0059] Examples of the "aromatic hydrocarbon group", the "aromatic
heterocyclic group", or the "fused polycyclic aromatic group" of
the "substituted or unsubstituted aromatic hydrocarbon group", the
"substituted or unsubstituted aromatic heterocyclic group", or the
"substituted or unsubstituted fused polycyclic aromatic group"
represented by A, B, and C in the structural formula (A-1) are
similar to those listed above as examples with respect to the
"aromatic hydrocarbon group", the "aromatic heterocyclic group", or
the "fused polycyclic aromatic group" represented by R in the
structural formulae (B-1) to (B-6). The same holds true for the
forms that the group can take.
[0060] Examples of the "substituent" of the "substituted aromatic
hydrocarbon group", the "substituted aromatic heterocyclic group",
or the "substituted fused polycyclic aromatic group" represented by
A, B, and C in the structural formula (A-1) are similar to those
listed above as examples with respect to the "substituent" of those
represented by R in the structural formulae (B-1) to (B-6). The
same holds true for the forms that the substituent can take.
[0061] Examples of the "aromatic hydrocarbon group", the "aromatic
heterocyclic group", or the "fused polycyclic aromatic group" of
the "substituted or unsubstituted aromatic hydrocarbon group", the
"substituted or unsubstituted aromatic heterocyclic group", or the
"substituted or unsubstituted fused polycyclic aromatic group"
represented by L in the structural formulae (B-1) to (B-6) are
similar to those listed above as examples with respect to the
"aromatic hydrocarbon group", the "aromatic heterocyclic group", or
the "fused polycyclic aromatic group" represented by R in the
structural formulae (B-1) to (B-6). The same holds true for the
forms that the group can take.
[0062] Examples of the "substituent" of the "substituted aromatic
hydrocarbon group", the "substituted aromatic heterocyclic group",
or the "substituted fused polycyclic aromatic group" represented by
L in the structural formulae (B-1) to (B-6) are similar to those
listed above as examples with respect to the "substituent" of those
represented by R in the structural formulae (B-1) to (B-6). The
same holds true for the forms that the substituent can take.
[0063] In the present invention, it is preferable that A in the
structural formula (A-1) is a group represented by the structural
formula (B-1). In this case, B and C may be the same or different,
and are each preferably a group represented by the structural
formula (C-1) or (C-2) below.
##STR00008##
[0064] In the structural formula (C-1), R.sup.1 and R.sup.2 may be
the same or different, and each represent a linear or branched
alkyl group having 1 to 6 carbon atoms; j is the number of R.sup.1s
and represents an integer of 0 to 2; and k is the number of
R.sup.2s and represents an integer of 0 to 2, where j+k is 0 or 2,
and when j+k is 2, R.sup.1s, R.sup.2s, or R.sup.1 and R.sup.2 are
located adjacent to each other and bonded to each other to form a
ring.
##STR00009##
[0065] In the structural formula (C-2), les may be the same or
different, and each represent a linear or branched alkyl group
having 1 to 6 carbon atoms; and 1 is the number of R.sup.3s and
represents 0, 2, or 4, where, when 1 is 2 or 4, R.sup.3s are
located adjacent to each other and bonded to each other to form a
ring.
[0066] The compound having a triarylamine structure and being
represented by the structural formula (A-1) and being suitable for
use in an organic EL device of the present invention can be used as
the materials of a hole injection layer, a hole transport layer,
and an electron blocking layer of the organic EL device. In
particular, having the high hole mobility, this compound is
preferable as the materials of a hole injection layer and a hole
transport layer.
[0067] The organic EL device of the present invention uses the
material for organic EL devices that has excellent hole injection
and transport performance, and excellent electron blocking
performance, as well as excellent stability and durability of a
thin film. Therefore, the organic EL device of the present
invention has higher hole transport efficiency of transporting
holes from the hole transport layer to the light emitting layer
than conventional organic EL devices, and, accordingly, has higher
light emission efficiency and a lower driving voltage, and hence
higher durability. The use of the compound having a triarylamine
structure and being represented by the structural formula (A-1)
makes it possible to realize an organic EL device having high
efficiency, a low driving voltage, and a long lifespan.
Advantageous Effects of Invention
[0068] With an organic EL device of the present invention, since a
compound having a specific triarylamine structure and being capable
of effectively performing the hole injection and transport
functions is selected, holes can be efficiently injected and
transported from the hole transport layer to the light emitting
layer, and therefore, it is possible to realize an organic EL
device having excellent hole injection and transport performance,
excellent stability and durability of a thin film, high efficiency,
a low driving voltage, and a long lifespan.
[0069] According to the present invention, it is possible to
improve the light emission efficiency, the driving voltage, and the
durability of an organic EL device.
BRIEF DESCRIPTION OF DRAWINGS
[0070] FIG. 1 is a schematic diagram showing the configuration of
an organic EL device of the present invention.
DESCRIPTION OF EMBODIMENTS
[0071] Specific examples of preferred compounds, of compounds
having a triarylamine structure and being represented by the
structural formula (A-1) and being suitable for use in an organic
EL device of the present invention, will be given below. However,
the present invention is not limited to these compounds.
##STR00010## ##STR00011## ##STR00012## ##STR00013## ##STR00014##
##STR00015## ##STR00016## ##STR00017## ##STR00018## ##STR00019##
##STR00020## ##STR00021## ##STR00022## ##STR00023## ##STR00024##
##STR00025## ##STR00026## ##STR00027## ##STR00028## ##STR00029##
##STR00030## ##STR00031## ##STR00032## ##STR00033## ##STR00034##
##STR00035## ##STR00036## ##STR00037## ##STR00038## ##STR00039##
##STR00040##
[0072] The compound having a triarylamine structure and being
represented by the general formula (A-1) can be purified using a
known method that is used to purify an organic compound, such as
purification through column chromatography, purification through
adsorption using silica gel, activated carbon, activated clay, or
the like, recrystallization or crystallization using a solvent, or
purification through sublimation. Identification of the compound
can be performed using NMR analysis or the like. It is preferable
to measure the melting point, the glass transition point (Tg), and
the work function as physical properties. The melting point is an
indicator of the vapor deposition properties. The glass transition
point (Tg) is an indicator of the stability in a thin film state.
The work function is an indicator of the hole transportability and
the electron blockability.
[0073] The melting point and the glass transition point (Tg) can be
measured using, for example, a powder and a high-sensitivity
differential scanning calorimeter (DSC3100SA manufactured by Bruker
AXS K.K.).
[0074] The work function can be obtained by, for example, forming a
100-nm thin film on an ITO substrate and performing the measurement
using an ionization potential measuring device (PYS-202
manufactured by Sumitomo Heavy Industries, Ltd.).
[0075] The organic EL device of the present invention may have a
structure in which an anode, a hole injection layer, a hole
transport layer, a light emitting layer, an electron transport
layer, an electron injection layer, and a cathode are sequentially
formed on a substrate; a structure in which an electron blocking
layer is further provided between the hole transport layer and the
light emitting layer; or a structure in which a hole blocking layer
is further provided between the light emitting layer and the
electron transport layer. In these multilayer structures, a single
organic layer can perform the functions of several layers. For
example, a configuration in which a single organic layer serves as
both the hole injection layer and the hole transport layer, a
configuration in which a single organic layer serves as both the
electron injection layer and the electron transport layer, and the
like may also be adopted. Moreover, it is possible to stack two or
more organic layers having the same function, and a configuration
in which two hole transport layers are stacked, a configuration in
which two light emitting layers are stacked, a configuration in
which two electron transport layers are stacked, and the like may
also be adopted.
[0076] For example, FIG. 1 shows a layer configuration of an
organic EL device in which an anode 2, a hole injection layer 3, a
hole transport layer 4, an electron blocking layer 5, a light
emitting layer 6, an electron transport layer 7, an electron
injection layer 8, and a cathode 9 are formed in this order on a
glass substrate 1. Hereinafter, the various layers constituting the
organic EL device of the present invention will be described.
[0077] (Anode 2)
[0078] An electrode material having a high work function, such as
ITO or gold, is used for the anode 2.
[0079] (Hole Injection Layer 3)
[0080] In addition to the compound having a triarylamine structure
of the present invention, known compounds can be used for the hole
injection layer 3, and examples thereof include: porphyrin
compounds typified by copper phthalocyanine; starburst
triphenylamine derivatives; arylamine compounds having a structure
containing two or more triphenylamine structures or carbazolyl
structures in the molecule, the triphenylamine or the carbazolyl
structures being linked via a single bond or a divalent group
having no heteroatom; and the like. It is also possible to use
acceptor type heterocyclic compounds such as
hexacyanoazatriphenylene, and coating type polymer materials such
as poly(3,4-ethylenedioxythiophene) (hereinafter abbreviated as
PEDOT)/poly(styrenesulfonate) (hereinafter abbreviated as PSS).
[0081] These compounds and materials may be used alone, or as a
mixture of two or more, to form a hole injection layer. In the case
where a mixture of two or more of these compounds and materials is
used to form a hole injection layer, a compound or material that is
p-doped with trisbromophenylamine hexachloroantimony, a radialene
derivative (see Patent Literature 5, for example), or the like; a
polymer compound having the structure of a benzidine derivative,
such as N,N'-diphenyl-N,N'-di(m-tolyl)-benzidine (hereinafter
abbreviated as TPD), in a partial structure thereof; or the like
may be used as one component of the mixture.
[0082] With these compounds and materials, a thin film can be
formed using vapor deposition, or another known method such as spin
coating or inkjet printing.
[0083] (Hole Transport Layer 4)
[0084] In addition to the compound having a triarylamine structure
of the present invention, known compounds having hole
transportability can also be used for the hole transport layer 4.
Examples of the known compounds having hole transportability
include benzidine derivatives such as TPD, NPD, and
N,N,N',N'-tetrabiphenylyl benzidine;
1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (hereinafter
abbreviated as TAPC); and arylamine compounds having a structure
containing two or more triphenylamine structures or carbazolyl
structures in the molecule, the triphenylamine or the carbazolyl
structures being linked via a single bond or a divalent group
having no heteroatom. Moreover, coating type polymer materials such
as PEDOT and PSS described above can also be used. These compounds
and materials may be used alone, or as a mixture of two or more, to
form a hole transport layer, and the formed layers can each be used
as a single layer. The hole transport layer 4 may have a structure
in which layers that are each formed using one of the above-listed
compounds and materials alone are stacked, a structure in which
layers that are each formed using a mixture of two or more of the
above-listed compounds and materials are stacked, or a structure in
which a layer that is formed using one of the above-listed
compounds and materials alone and a layer that is formed using a
mixture of two or more of the above-listed compounds and materials
are stacked. With these compounds and materials, a thin film can be
formed using vapor deposition, or another known method such as spin
coating or inkjet printing.
[0085] Moreover, in addition to normally used compounds and
materials, a compound or material that is p-doped with
trisbromophenylamine hexachloroantimony, a radialene derivative
(see Patent Literature 5, for example), or the like; a polymer
compound having the structure of a benzidine derivative, such as
TPD, in a partial structure thereof; and the like may further be
used for the hole transport layer 4.
[0086] (Electron Blocking Layer 5)
[0087] In addition to the compound having a triarylamine structure
of the present invention, known compounds having an electron
blocking effect can also be used for the electron blocking layer 5.
Examples of the known compounds having an electron blocking effect
include compounds having an electron blocking effect, such as
carbazole derivatives such as
4,4',4''-tri(N-carbazolyl)triphenylamine (hereinafter abbreviated
as TCTA), 9,9-bis[4-(carbazole-9-yl)phenyl]fluorene,
1,3-bis(carbazole-9-yl)benzene (hereinafter abbreviated as mCP),
and 2,2-bis(4-carbazole-9-ylphenyl)adamantane (hereinafter
abbreviated as Ad-Cz); and compounds that have a triphenylsilyl
group and a triarylamine structure and are typified by
9-[4-(carbazole-9-yl)phenyl]-9-[4-(triphenyl
silyl)phenyl]-9H-fluorene. These compounds and materials may be
used alone, or as a mixture of two or more, to form an electron
blocking layer, and the formed layers can each be used as a single
layer. The electron blocking layer 5 may have a structure in which
layers that are each formed using one of the above-listed materials
alone are stacked, a structure in which layers that are each formed
using a mixture of two or more of the above-listed materials are
stacked, or a structure in which a layer that is formed using one
of the above-listed materials alone and a layer that is formed
using a mixture of two or more of the above-listed materials are
stacked. With these compounds, a thin film can be formed using
vapor deposition, or another known method such as spin coating or
inkjet printing.
[0088] (Light Emitting Layer 6)
[0089] In addition to the compound having a triarylamine structure
of the present invention, known light emitting materials can also
be used for the light emitting layer 6. Examples of the known light
emitting materials include metal complexes of quinolinol
derivatives such as Alq.sub.3, various types of metal complexes, an
anthracene derivative, a bisstyrylbenzene derivative, a pyrene
derivative, an oxazole derivative, and a poly(p-phenylene vinylene
derivative). Moreover, the light emitting layer 6 may also be
formed using a host material and a dopant material. As the host
material, an anthracene derivative is preferably used. In addition,
the above-listed light emitting materials including the compound
having a triarylamine structure of the present invention, as well
as a heterocyclic compound having an indole ring as a partial
structure of a fused ring, a heterocyclic compound having a
carbazole ring as a partial structure of a fused ring, a carbazole
derivative, a thiazole derivative, a benzimidazole derivative, a
polydialkylfluorene derivative, and the like can be used as the
host material. As the dopant material, quinacridone, coumalin,
rubrene, perylene, and derivatives thereof; a benzopyran
derivative; a rhodamine derivative; an aminostyryl derivative; and
the like may be used. These compounds and materials may be used
alone, or as a mixture of two or more, to form a light emitting
layer, and the formed layers can each be used as a single layer.
The light emitting layer 6 may have a structure in which layers
that are each formed using one of the above-listed compounds and
materials alone are stacked, a structure in which layers that are
each formed using a mixture of two or more of the above-listed
compounds and materials are stacked, or a structure in which a
layer that is formed using one of the above-listed compounds and
materials alone and a layer that is formed using a mixture of two
or more of the above-listed compounds and materials are
stacked.
[0090] Moreover, a phosphorescent emitter can also be used as a
light emitting material. As the phosphorescent emitter, a
phosphorescent emitter of a metal complex of iridium, platinum, or
the like can be used. Examples include a green phosphorescent
emitter such as Ir(ppy).sub.3, a blue phosphorescent emitter such
as Flrpic or FIr6, and a red phosphorescent emitter such as
Btp.sub.2Ir (acac). In this case, host materials having hole
injectability and transportability, such as carbazole derivatives
such as 4,4'-di(N-carbazolyl)biphenyl (hereinafter abbreviated as
CBP), TCTA, and mCP, as well as compounds having a benzazole ring
structure and a pyridoindole ring structure, may be used as the
host material. Also, host materials having electron
transportability, such as p-bis(triphenylsilyl)benzene (hereinafter
abbreviated as UGH2) and
2,2',2''-(1,3,5-phenylene)-tris(1-phenyl-1H-benzimidazole)
(hereinafter abbreviated as TPBI), may be used as the host
material. When a phosphorescent emitter such as those listed above
is used as the light emitting material, a high-performance organic
EL device can be produced.
[0091] In order to avoid concentration quenching, it is preferable
that doping of the host material with a phosphorescent light
emitting material is performed within a range of 1 to 30 wt % with
respect to the entire light emitting layer, and it is preferable to
perform the doping through co-deposition.
[0092] As the light emitting material, a material that emits
delayed fluorescence such as a CDCB derivative, specifically,
PIC-TRZ, CC2TA, PXZ-TRZ, 4CzIPN, or the like can also be used (see
Non-Patent Literature 3, for example). With these materials, a thin
film can be formed using vapor deposition, or another known method
such as spin coating or inkjet printing.
[0093] (Hole Blocking Layer)
[0094] A hole blocking layer (not shown in FIG. 1) may be provided
between the light emitting layer 6 and the electron transport layer
7. A known compound having a hole blocking effect can be used for
the hole blocking layer. Examples of the known compound having a
hole blocking effect include a phenanthroline derivative, such as
bathocuproine (hereinafter abbreviated as BCP); a metal complex of
a quinolinol derivative, such as aluminum (III)
bis(2-methyl-8-quinolinate)-4-phenylphenolate (hereinafter
abbreviated as BAlq); various types of rare-earth complexes; an
oxazole derivative; a triazole derivative; a triazine derivative; a
pyrimidine derivative; an oxadiazole derivative; a benzazole
derivative; and the like. These compounds may also serve as the
material of the electron transport layer. These compounds may be
used alone, or as a mixture of two or more, to form a hole blocking
layer, and the formed layers can each be used as a single layer.
The hole blocking layer may have a structure in which layers that
are each formed using one of the above-listed compounds alone are
stacked, a structure in which layers that are each formed using a
mixture of two or more of the above-listed compounds are stacked,
or a structure in which a layer that is formed using one of the
above-listed compounds alone and a layer that is formed using a
mixture of two or more of the above-listed compounds are stacked.
With these materials, a thin film can be formed using vapor
deposition, or another known method such as spin coating or inkjet
printing.
[0095] (Electron Transport Layer 7)
[0096] A known compound having electron transportability can be
used for the electron transport layer 7. Examples of the known
compound having electron transportability include metal complexes
of quinolinol derivatives, such as Alq.sub.3 and BAlq; various
types of metal complexes; a triazole derivative; a triazine
derivative; a pyrimidine derivative; an oxadiazole derivative; a
pyridine derivative; a benzimidazole derivative; a benzazole
derivative; a thiadiazole derivative; an anthracene derivative; a
carbodiimide derivative; a quinoxaline derivative; a pyridoindole
derivative; a phenanthroline derivative; a silole derivative; and
the like. These compounds may be used alone, or as a mixture of two
or more, to form an electron transport layer, and the formed layers
can each be used as a single layer. The electron transport layer
may have a structure in which layers that are each formed using one
of the above-listed compounds alone are stacked, a structure in
which layers that are each formed using a mixture of two or more of
the above-listed compounds are stacked, or a structure in which a
layer that is formed using one of the above-listed compounds alone
and a layer that is formed using a mixture of two or more of the
above-listed compounds are stacked. With these materials, a thin
film can be formed using vapor deposition, or another known method
such as spin coating or inkjet printing.
[0097] (Electron Injection Layer 8)
[0098] An alkali metal salt such as lithium fluoride or cesium
fluoride; an alkaline earth metal salt such as magnesium fluoride;
a metal complex of a quinolinol derivative such as lithium
quinolinol; a metal oxide such as aluminum oxide; or a metal such
as ytterbium (Yb), samarium (Sm), calcium (Ca), strontium (Sr), or
cesium (Cs) can be used for the electron injection layer 8. The
electron injection layer 8 can be omitted by selecting a suitable
combination of the electron transport layer and the cathode.
[0099] Furthermore, for the electron injection layer 8 and the
electron transport layer 7, a material obtained by n-doping a
material normally used for those layers with a metal such as cesium
can be used.
[0100] (Cathode 9)
[0101] An electrode material having a low work function, such as
aluminum; an alloy having an even lower work function, such as a
magnesium-silver alloy, a magnesium-calcium alloy, a
magnesium-indium alloy, or an aluminum-magnesium alloy; or an
electrode material, such as ITO or IZO, is used for the cathode
9.
EXAMPLES
[0102] Hereinafter, embodiments of the present invention will be
described in greater detail using examples. However, the present
invention is not limited to the examples below without departing
from the gist thereof.
Example 1
Synthesis of
N,N-bis([1,1'-biphenyl]-4-yl)-5'-phenyl-(1,1':2',1''-triphenyl)-4-amine
(Compound-1)
[0103] First, 5.00 g of bis(4-biphenylyl)amine, 6.59 g of
4-bromo-5'-phenyl-1,1':2',1''-terphenyl, 50 ml of toluene, 1.79 g
of sodium t-butoxide, 0.13 g of t-butylphosphine (50 wt % toluene
solution), and 0.07 g of palladium (II) acetate were added to a
nitrogen-purged reaction vessel and stirred for 3 hours under heat
reflux. Next, 10 g each of silica gel and activated clay were added
to the reaction liquid, which was then stirred for 10 minutes and
subsequently subjected to Celite filtration at 80.degree. C. Then,
crystallization was performed by adding 180 ml of acetone to the
concentrated filtrate, and a solid was thus obtained. The obtained
solid was purified by column chromatography using an
n-heptane/dichloromethane mixed solvent. The concentrated solid was
dissolved in 20 ml of dichloromethane, and a crystallization
operation was then performed by adding 200 ml of n-heptane. Thus,
5.4 g (with a yield of 56%) of a white solid of
N,N-bis([1,1'-biphenyl]-4-yl)-5'-phenyl-(1,1':2',1''-triphenyl)-4-amine
(Compound-1) was obtained.
##STR00041##
[0104] The structure of the obtained white solid was identified
using NMR.
[0105] In .sup.1H-NMR (DMSO-d.sub.6), the following signals of 35
hydrogens were detected.
[0106] .delta. (ppm)=7.80-7.72 (4H), 7.67-7.62 (8H), 7.53-7.40
(8H), 7.36-7.28 (5H), 7.21-7.09 (8H), 6.98 (2H)
Example 2
Synthesis of
N-([1,1'-biphenyl]-4-yl)-9,9-dimethyl-N-(5'-phenyl-[1,1':2',1''-triphenyl-
]-4-yl)-9H-fluor ene-2-amine (Compound-2)
[0107] First, 6.10 g of 2-(4-biphenylyl)amino-9,9-dimethylfluorene,
7.15 g of 4-bromo-5'-phenyl-1,1':2',1''-terphenyl, 61 ml of
toluene, 1.95 g of sodium t-butoxide, 0.14 g of t-butylphosphine
(50 wt % toluene solution), and 0.08 g of palladium (II) acetate
were added to a nitrogen-purged reaction vessel and stirred for 3
hours under heat reflux. Next, 10 g each of silica gel and
activated clay were added to the reaction liquid, which was then
stirred for 10 minutes and subsequently subjected to Celite
filtration at 80.degree. C. Then, a crystallization operation was
performed by adding 220 ml of acetone to the concentrated filtrate,
and a solid was thus obtained. The obtained solid was purified by
column chromatography using an n-heptane/dichloromethane mixed
solvent. The concentrated solid was dissolved in 22 ml of
dichloromethane, and a crystallization operation was then performed
by adding 220 ml of n-heptane. A similar crystallization operation
was performed again. Thus, 2.2 g (with a yield of 19%) of a white
solid of
N-([1,1'-biphenyl]-4-yl)-9,9-dimethyl-N-(5'-phenyl-[1,1':2',1''-triphenyl-
]-4-yl)-9H-fluor ene-2-amine (Compound-2) was obtained.
##STR00042##
[0108] The structure of the obtained white solid was identified
using NMR.
[0109] In .sup.1H-NMR (DMSO-d.sub.6), the following signals of 39
hydrogens were detected.
[0110] .delta. (ppm)=7.73-7.56 (10H), 7.49-7.42 (10H), 7.35-7.22
(6H), 7.11-7.07 (4H), 6.98-6.96 (3H)
Example 3
Synthesis of
N,N-bis(4-[naphthalene-1-yl]phenyl)-5'-phenyl-(1,1':2',1''-triphenyl)-4-a-
mine (Compound-3)
[0111] First, 9.00 g of N,N-bis[4-(naphthalene-1-yl)phenyl]amine,
9.87 g of 4-bromo-5'-phenyl-1,1':2',1''-terphenyl, 90 ml of
toluene, 2.46 g of sodium t-butoxide, 0.17 g of t-butylphosphine
(50 wt % toluene solution), and 0.10 g of palladium (II) acetate
were added to a nitrogen-purged reaction vessel and stirred for 3
hours under heat reflux. Next, 15 g each of silica gel and
activated clay were added to the reaction liquid, which was then
stirred for 10 minutes and subsequently subjected to Celite
filtration at 80.degree. C. The filtrate was concentrated, and then
purified by column chromatography using an
n-heptane/dichloromethane mixed solvent. The concentrated solid was
dissolved in 30 ml of dichloromethane, which was then added
dropwise to 300 ml of methanol, and a solid was thus obtained. The
obtained solid was purified in a similar manner. Thus, 13.0 g (with
a yield of 83.9%) of a white solid of
N,N-bis(4-[naphthalene-1-yl]phenyl)-5'-phenyl-(1,1':2',1''-triphenyl)-4-a-
mine (Compound-3) was obtained.
##STR00043##
[0112] The structure of the obtained white solid was identified
using NMR.
[0113] In .sup.1H-NMR (DMSO-d.sub.6), the following signals of 39
hydrogens were detected.
[0114] .delta. (ppm)=8.02-7.94 (6H), 7.82-7.75 (4H), 7.64-7.47
(15H), 7.43-7.21 (12H), 7.16-7.10 (2H)
Example 4
Synthesis of
N,N-bis(4-[naphthalene-2-yl]phenyl)-5'-phenyl-(1,1':2',1''-triphenyl)-4-a-
mine (Compound-4)
[0115] First, 10.00 g of N,N-bis[4-(naphthalene-2-yl)phenyl]amine,
10.97 g of 4-bromo-5'-phenyl-1,1':2',1''-terphenyl, 100 ml of
toluene, 2.74 g of sodium t-butoxide, 0.19 g of t-butylphosphine
(50 wt % toluene solution), and 0.11 g of palladium (II) acetate
were added to a nitrogen-purged reaction vessel and stirred for 3
hours under heat reflux. Next, 17 g each of silica gel and
activated clay were added to the reaction liquid, which was then
stirred for 10 minutes and subsequently subjected to Celite
filtration at 80.degree. C. Then, a crystallization operation was
performed by adding 340 ml of acetone to the concentrated filtrate,
and a solid was thus obtained. The obtained solid was dissolved in
34 ml of toluene, and a crystallization operation was then
performed by adding 340 ml of acetone. Thus, 8.3 g (with a yield of
48%) of a white solid of
N,N-bis(4-[naphthalene-2-yl]phenyl)-5'-phenyl-(1,1':2',1''-triphenyl)-4-a-
mine (Compound-4) was obtained.
##STR00044##
[0116] The structure of the obtained white solid was identified
using NMR.
[0117] In .sup.1H-NMR (DMSO-d.sub.6), the following signals of 39
hydrogens were detected.
[0118] .delta. (ppm)=8.21 (2H), 8.01-7.92 (6H), 7.88-7.74 (10H),
7.57-7.48 (7H), 7.43-7.30 (4H), 7.28-7.17 (8H), 7.03 (2H)
Example 5
<Synthesis of
N-(4-(naphthalene-1-yl)phenyl)-N-(5'-phenyl[1,1':2',1''-terphenyl]-4-yl)p-
henanthrene-9-amine (Compound-58)>
[0119] First, 8.5 g of
N-(4-(naphthalene-1-yl)phenyl)-N-(5'-phenyl[1,1':2',1''-terphenyl]-4-amin-
e, 4.8 g of 9-bromophenanthrene, 85 ml of toluene, 2.3 g of sodium
t-butoxide, 0.3 g of t-butylphosphine (50 wt % toluene solution),
and 0.1 g of palladium (II) acetate were added to a nitrogen-purged
reaction vessel and stirred for 3 hours under heat reflux. Celite
filtration was performed at 80.degree. C. Activated clay and silica
gel were added to the filtrate, and purification through adsorption
was then performed. The filtrate was concentrated, and the residue
was crystalized using acetone. Thus, 8.3 g (with a yield of 73%) of
a white solid of
N-(4-(naphthalene-1-yl)phenyl)-N-(5'-phenyl[1,1':2',1''-terphenyl]-4-yl)p-
henanthrene-9-amine (Compound-58) was obtained.
##STR00045##
[0120] The structure of the obtained white solid was identified
using NMR.
[0121] In .sup.1H-NMR (CDCl.sub.3), the following signals of 37
hydrogens were detected.
[0122] .delta. (ppm)=8.75-8.84 (2H), 8.16-8.20 (1H), 8.05-8.09
(1H), 7.91-7.95 (3H), 7.12-7.78 (3 OH)
Example 6
Synthesis of
N-(4-(naphthalene-2-yl)phenyl)-N-(5'-phenyl[1,1':2',1''-terphenyl]-4-yl)p-
henanthrene-9-amine (Compound-59)
[0123] First, 8.0 g of
N-(4-(naphthalene-2-yl)phenyl)-N-(5'-phenyl[1,1':2',1''-terphenyl]-4-amin-
e, 4.5 g of 9-bromophenanthrene, 80 ml of toluene, 2.2 g of sodium
t-butoxide, 0.2 g of t-butylphosphine (50 wt % toluene solution),
and 0.1 g of palladium (II) acetate were added to a nitrogen-purged
reaction vessel and stirred for 3 hours under heat reflux. Celite
filtration was performed at 80.degree. C. Activated clay and silica
gel were added to the filtrate, and purification through adsorption
was then performed. The filtrate was concentrated, and the residue
was crystalized using toluene-acetone. Thus, 6.6 g (with a yield of
62%) of a white solid of
N-((4-naphthalene-2-yl)phenyl)-N-(5'-phenyl[1,1':2',1''-terphenyl]-4-yl)p-
henanthrene-9-amine (Compound-59) was obtained.
##STR00046##
[0124] The structure of the obtained white solid was identified
using NMR.
[0125] In .sup.1H-NMR (CDCl.sub.3), the following signals of 37
hydrogens were detected.
[0126] .delta. (ppm)=8.74-8.83 (2H), 8.12-8.17 (1H), 8.30 (1H),
7.21-7.94 (29H), 7.08-7.14 (4H)
Example 7
Synthesis of 9,9-dimethyl-N-phenyl-N-(4'-phenyl[1,
1':2',1'':4'',1'''-quaterphenyl]-4''-yl)-9H-fluorene-2-amine
(Compound-71)
[0127] First, 4.5 g of 9,9-dimethyl-N-phenyl-9H-fluorene-2-amine,
7.6 g of 4''-bromo4'-phenyl-[1,1':2',1'':4'',1'''-quaterphenyl], 45
ml of toluene, 1.8 g of sodium t-butoxide, 0.13 g of
t-butylphosphine (50 wt % toluene solution), and 0.07 g of
palladium (II) acetate were added to a nitrogen-purged reaction
vessel and stirred overnight under heat reflux. The reaction liquid
was cooled to room temperature, washed with water, and dried over
anhydrous magnesium sulfate. The desiccant was removed by
filtration, and the filtrate was concentrated. The residue was
purified by column chromatography.
[0128] Thus, 6.5 g (with a yield of 62%) of a white solid of
9,9-dimethyl-N-phenyl-N-(4'-phenyl[1,1':2',1'':4'',1'''-quaterphenyl]-4''-
-yl)-9H-fluorene-2-amine (Compound-71) was obtained.
##STR00047##
[0129] The structure of the obtained white solid was identified
using NMR.
[0130] In .sup.1H-NMR (CDCl.sub.3), the following signals of 39
hydrogens were detected.
[0131] .delta. (ppm)=7.51-7.80 (13H), 7.22-7.48 (18H), 7.08-7.16
(2H), 1.50 (6H)
Example 8
<Synthesis of
N-([1,1'-biphenyl]-4-yl)-N-(4-(naphthalene-2-yl)phenyl)-4'-phenyl-[1,1':2-
',1'':4'',1'''-quaterphenyl]-4'''-amine (Compound-72)>
[0132] First, 5.1 g of
N-(4-(naphthalene-2-yl)phenyl)-[1,1'-biphenyl]-4-amine, 6.7 g of
4''-bromo4'-phenyl-[1,1':2',1'':4'',1'''-quaterphenyl], 51 ml of
toluene, 1.6 g of sodium t-butoxide, 0.11 g of t-butylphosphine (50
wt % toluene solution), and 0.06 g of palladium (II) acetate were
added to a nitrogen-purged reaction vessel and stirred overnight
under heat reflux. The reaction liquid was cooled to room
temperature, and insoluble matter was removed by Celite filtration.
Activated carbon was added to the filtrate, and purification
through adsorption was then performed. The filtrate was
concentrated, and the residue was crystalized using
toluene-acetone. Thus, 7.6 g (with a yield of 74%) of a white solid
of
N-([1,1'-biphenyl]-4-yl)-N-(4-(naphthalene-2-yl)phenyl)-4-phenyl-[1,1:2',-
1'':4'',1'''-quaterphenyl]-4'''-amine (Compound-72) was
obtained.
##STR00048##
[0133] The structure of the obtained white solid was identified
using NMR. In .sup.1H-NMR (CDCl.sub.3), the following signals of 41
hydrogens were detected.
[0134] .delta. (ppm)=8.11 (1H), 7.91-7.98 (3H), 7.65-7.83 (9H),
7.28-7.62 (28H)
Example 9
Synthesis of
N-phenyl-N-(4'-phenyl-[1,1':2',1'':4'',1'''-quaterphenyl]-4'''-yl)phenant-
hrene-9-amine (Compound-77)
[0135] First, 5.0 g of N-phenyl-phenanthrene-9-amine, 9.4 g of
4''-bromo4'-phenyl-[1,1':2',1'':4'',1'''-quaterphenyl], 50 ml of
toluene, 2.1 g of sodium t-butoxide, 0.15 g of t-butylphosphine (50
wt % toluene solution), and 0.08 g of palladium (II) acetate were
added to a nitrogen-purged reaction vessel and stirred overnight
under heat reflux. The reaction liquid was cooled to 80.degree. C.,
and insoluble matter was removed by Celite filtration. The filtrate
was concentrated, and the residue was purified by column
chromatography. Thus, 3.8 g (with a yield of 32%) of a white solid
of
N-phenyl-N-(4'-phenyl-[1,1':2',1'':4'',1'''-quaterphenyl]-4'''-yl)phenant-
hrene-9-amine (Compound-77) was obtained.
##STR00049##
[0136] The structure of the obtained white solid was identified
using NMR.
[0137] In .sup.1H-NMR (CDCl.sub.3), the following signals of 35
hydrogens were detected.
[0138] .delta. (ppm)=8.73-8.82 (2H), 8.12-8.16 (1H), 7.40-7.83
(18H), 7.18-7.32 (13H), 7.02-7.08 (1H)
Example 10
Synthesis of N-(4-(naphthalene-1-yl)phenyl)-N-(4'-phenyl-[1,
1':2'',1'':4'''', 1''''-quaterphenyl]-4'''-yl)phenanthrene-2-amine
(Compound-86)
[0139] First, 6.0 g of
N-(4-(naphthalene-1-yl)phenyl)-phenanthrene-2-amine, 7.3 g of
4''-bromo4'-phenyl-[1,1':2',1'':4'',1'''-quaterphenyl], 60 ml of
toluene, 1.7 g of sodium t-butoxide, 0.12 g of t-butylphosphine (50
wt % toluene solution), and 0.07 g of palladium (II) acetate were
added to a nitrogen-purged reaction vessel and stirred overnight
under heat reflux. The reaction liquid was cooled to 80.degree. C.,
and insoluble matter was removed by Celite filtration. The filtrate
was concentrated, and the residue was purified by column
chromatography. Thus, 8.0 g (with a yield of 68%) of a yellowish
white solid of
N-(4-(naphthalene-1-yl)phenyl)-N-(4'-phenyl-[1,1':2',1'':4'',1'''-quaterp-
henyl]-4'''-yl)phenanthrene-2-amine (Compound-86) was obtained.
##STR00050##
[0140] The structure of the obtained white solid was identified
using NMR.
[0141] In .sup.1H-NMR (CDCl.sub.3), the following signals of 41
hydrogens were detected.
[0142] .delta. (ppm)=8.62-8.67 (2H), 8.11-8.16 (1H), 7.88-7.99
(3H), 7.27-7.79 (35H)
Example 11
[0143] The melting point and the glass transition point (Tg) of
each of the compounds synthesized in the above-described examples,
the compounds having a triarylamine structure and being represented
by the structural formula (A-1), were measured using a
high-sensitivity differential scanning calorimeter (DSC3100SA
manufactured by Bruker AXS K.K.). Table 1 shows the results.
TABLE-US-00001 TABLE 1 Compound Melting point (.degree. C.) Tg
(.degree. C.) Ex. 1 Compound-1 -- 96.8 Ex. 2 Compound-2 -- 102.0
Ex. 3 Compound-3 -- 112.2 Ex. 4 Compound-4 220.6 107.1 Ex. 5
Compound-58 -- 131.2 Ex. 6 Compound-59 -- 129.7 Ex. 7 Compound-71
-- 114.1 Ex. 8 Compound-72 228.3 122.0 Ex. 9 Compound-77 -- 125.1
Ex. 10 Compound-86 -- 139.0
[0144] The compounds synthesized in Examples 1 to 10, the compounds
having a triarylamine structure and being represented by the
structural formula (A-1), had a glass transition point of
95.degree. C. or more, which indicated that these compounds were
stable in a thin film state.
Example 12
[0145] A vapor-deposited film with a thickness of 100 nm was formed
on an ITO substrate using each of the compounds synthesized in the
above-described examples, the compounds having a triarylamine
structure and being represented by the structural formula (A-1),
and the work function was measured using an ionization potential
measuring device (PYS-202 manufactured by Sumitomo Heavy
Industries, Ltd.). Table 2 shows the results.
TABLE-US-00002 TABLE 2 Compound Work function (eV) Ex. 1 Compound-1
5.70 Ex. 2 Compound-2 5.63 Ex. 3 Compound-3 5.73 Ex. 4 Compound-4
5.67 Ex. 5 Compound-58 5.75 Ex. 6 Compound-59 5.72 Ex. 7
Compound-71 5.65 Ex. 8 Compound-72 5.68 Ex. 9 Compound-77 5.81 Ex.
10 Compound-86 5.69
[0146] The compounds synthesized in Examples 1 to 10, the compounds
having a triarylamine structure and being represented by the
structural formula (A-1), each exhibited an energy level higher
than 5.4 eV, which is the work function of common hole transport
materials such as NPD and TPD. This means that these compounds had
good hole transport capability.
[0147] The work functions of these compounds were between the work
function (5.0 eV) of ITO used as the anode and the work function
(6.0 eV) of the compound (EMH-1) used as the light emitting layer.
This means that these compounds had good hole injection
capability.
[0148] The work functions of these compounds were the values close
to the work function (6.0 eV) of the compound (EMH-1) used as the
light emitting layer. This means that these compounds were also
favorable as the material of the light emitting layer.
Example 13
[0149] An organic EL device was prepared using the compound
(Compound-1) of Example 1. The organic EL device had the
configuration shown in FIG. 1, and was prepared in the following
manner. An ITO electrode serving as an anode 2 was formed on a
glass substrate 1 beforehand, and a hole injection layer 3, a hole
transport layer 4, an electron blocking layer 5, a light emitting
layer 6, an electron transport layer 7, an electron injection layer
8, and a cathode (aluminum electrode) 9 were vapor-deposited in
this order on the ITO electrode.
[0150] Specifically, a glass substrate 1 on which an ITO film with
a thickness of 150 nm was formed was ultrasonically cleaned in
isopropyl alcohol for 20 minutes, and then dried for 10 minutes on
a hot plate heated to 200.degree. C. After that, UV/ozone treatment
was performed for 15 minutes. Then, the glass substrate with ITO
was attached inside a vacuum vapor deposition machine, and the
pressure was reduced to 0.001 Pa or less. Subsequently, an electron
acceptor (Acceptor-1) having the structural formula below and a
compound (HTM-1) having the structure below were vapor-deposited so
as to cover the anode 2 through binary vapor deposition at such
vapor deposition rates that the ratio of the vapor deposition rate
of Acceptor-1 to the vapor deposition rate of HTM-1 was 3:97, and a
hole injection layer 3 with a thickness of 30 nm was thus formed.
The compound (HTM-1) was formed on this hole injection layer 3 as a
hole transport layer 4 with a thickness of 40 nm. The compound
(Compound-1) of Example 1 was formed on this hole transport layer 4
as an electron blocking layer 5 with a thickness of 5 nm. A
compound EMD-1 having the structural formula below and a compound
EMH-1 having the structural formula below were vapor-deposited on
this electron blocking layer 5 through binary vapor deposition at
such vapor deposition rates that the ratio of the vapor deposition
rate of EMD-1 to the vapor deposition rate of EMH-1 was 5:95, and a
light emitting layer 6 with a thickness of 20 nm was thus formed. A
compound (ETM-1) having the structural formula below and a compound
(ETM-2) having the structural formula below were vapor-deposited on
this light emitting layer 6 through binary vapor deposition at such
vapor deposition rates that the ratio of the vapor deposition rate
of ETM-1 to the vapor deposition rate of ETM-2 was 50:50, and an
electron transport layer 7 with a thickness of 30 nm was thus
formed. Lithium fluoride was formed on this electron transport
layer 7 as an electron injection layer 8 with a thickness of 1 nm.
Finally, aluminum was vapor-deposited to a thickness of 100 nm to
thereby form a cathode 9. The characteristics of the prepared
organic EL device were measured in the atmosphere at ordinary
temperature. Table 3 collectively shows the measurement results of
light emission characteristics that were obtained when a DC voltage
was applied to the prepared organic EL device.
##STR00051## ##STR00052## ##STR00053##
Example 14
[0151] An organic EL device was prepared under similar conditions
to those of Example 13, except that the compound (Compound-1) of
Example 1 serving as the material of the electron blocking layer 5
was replaced with the compound (Compound-2) of Example 2. The
characteristics of the prepared organic EL device were measured in
the atmosphere at ordinary temperature. Table 3 collectively shows
the measurement results of light emission characteristics that were
obtained when a DC voltage was applied to the prepared organic EL
device.
Example 15
[0152] An organic EL device was prepared under similar conditions
to those of Example 13, except that the compound (Compound-1) of
Example 1 serving as the material of the electron blocking layer 5
was replaced with the compound (Compound-3) of Example 3. The
characteristics of the prepared organic EL device were measured in
the atmosphere at ordinary temperature. Table 3 collectively shows
the measurement results of light emission characteristics that were
obtained when a DC voltage was applied to the prepared organic EL
device.
Example 16
[0153] An organic EL device was prepared under similar conditions
to those of Example 13, except that the compound (Compound-1) of
Example 1 serving as the material of the electron blocking layer 5
was replaced with the compound (Compound-4) of Example 4. The
characteristics of the prepared organic EL device were measured in
the atmosphere at ordinary temperature. Table 3 collectively shows
the measurement results of light emission characteristics that were
obtained when a DC voltage was applied to the prepared organic EL
device.
Example 17
[0154] An organic EL device was prepared under similar conditions
to those of Example 13, except that the compound (Compound-1) of
Example 1 serving as the material of the electron blocking layer 5
was replaced with the compound (Compound-58) of Example 5. The
characteristics of the prepared organic EL device were measured in
the atmosphere at ordinary temperature. Table 3 collectively shows
the measurement results of light emission characteristics that were
obtained when a DC voltage was applied to the prepared organic EL
device.
Example 18
[0155] An organic EL device was prepared under similar conditions
to those of Example 13, except that the compound (Compound-1) of
Example 1 serving as the material of the electron blocking layer 5
was replaced with the compound (Compound-59) of Example 6. The
characteristics of the prepared organic EL device were measured in
the atmosphere at ordinary temperature. Table 3 collectively shows
the measurement results of light emission characteristics that were
obtained when a DC voltage was applied to the prepared organic EL
device.
Example 19
[0156] An organic EL device was prepared under similar conditions
to those of Example 13, except that the compound (Compound-1) of
Example 1 serving as the material of the electron blocking layer 5
was replaced with the compound (Compound-71) of Example 7. The
characteristics of the prepared organic EL device were measured in
the atmosphere at ordinary temperature. Table 3 collectively shows
the measurement results of light emission characteristics that were
obtained when a DC voltage was applied to the prepared organic EL
device.
Example 20
[0157] An organic EL device was prepared under similar conditions
to those of Example 13, except that the compound (Compound-1) of
Example 1 serving as the material of the electron blocking layer 5
was replaced with the compound (Compound-72) of Example 8. The
characteristics of the prepared organic EL device were measured in
the atmosphere at ordinary temperature. Table 3 collectively shows
the measurement results of light emission characteristics that were
obtained when a DC voltage was applied to the prepared organic EL
device.
Example 21
[0158] An organic EL device was prepared under similar conditions
to those of Example 13, except that the compound (Compound-1) of
Example 1 serving as the material of the electron blocking layer 5
was replaced with the compound (Compound-77) of Example 9. The
characteristics of the prepared organic EL device were measured in
the atmosphere at ordinary temperature. Table 3 collectively shows
the measurement results of light emission characteristics that were
obtained when a DC voltage was applied to the prepared organic EL
device.
Example 22
[0159] An organic EL device was prepared under similar conditions
to those of Example 13, except that the compound (Compound-1) of
Example 1 serving as the material of the electron blocking layer 5
was replaced with the compound (Compound-86) of Example 10. The
characteristics of the prepared organic EL device were measured in
the atmosphere at ordinary temperature. Table 3 collectively shows
the measurement results of light emission characteristics that were
obtained when a DC voltage was applied to the prepared organic EL
device.
Comparative Example 1
[0160] For comparison, an organic EL device was prepared under
similar conditions to those of Example 13, except that the compound
(Compound-1) of Example 1 serving as the material of the electron
blocking layer 5 was replaced with HTM-1, and the electron blocking
layer 5 was formed with a thickness of 5 nm. The characteristics of
the prepared organic EL device were measured in the atmosphere at
ordinary temperature. Table 3 collectively shows the measurement
results of light emission characteristics that were obtained when a
DC voltage was applied to the prepared organic EL device.
Comparative Example 2
[0161] For comparison, an organic EL device was prepared under
similar conditions to those of Example 13, except that the compound
(Compound-1) of Example 1 serving as the material of the electron
blocking layer 5 was replaced with a compound (HTM-2) having the
structural formula below. The characteristics of the prepared
organic EL device were measured in the atmosphere at ordinary
temperature. Table 3 collectively shows the measurement results of
light emission characteristics that were obtained when a DC voltage
was applied to the prepared organic EL device.
##STR00054##
[0162] With use of the organic EL devices prepared in Examples 13
to 22 and Comparative Examples 1 and 2, the device lifespan was
measured. Table 3 collectively shows the results. The device
lifespan was defined as follows: when constant current driving was
performed with the light emission luminance (initial luminance)
when light emission started being set to 2,000 cd/m.sup.2, the time
taken for light emission luminance to decay to 1,900 cd/m.sup.2
(corresponding to 95% of the initial luminance being set to 100%:
at a decay of 95%) was measured as the device lifespan.
TABLE-US-00003 TABLE 3 Light emission Power Device Luminance
efficiency efficiency lifespan Electron Voltage [V] [cd/m.sup.2]
[cd/A] [lm/W] at a decay blocking layer (@10 mA/cm.sup.2) (@10
mA/cm.sup.2) (@10 mA/cm.sup.2) (@10 mA/cm.sup.2) of 95% Ex. 13
Compound-1 3.63 812 8.12 7.04 237 hrs. Ex. 14 Compound-2 3.63 830
8.30 7.18 241 hrs. Ex. 15 Compound-3 3.65 829 8.28 7.14 255 hrs.
Ex. 16 Compound-4 3.63 832 8.32 7.21 247 hrs. Ex. 17 Compound-58
3.65 837 8.37 7.21 236 hrs. Ex. 18 Compound-59 3.60 828 8.28 7.22
244 hrs. Ex. 19 Compound-71 3.64 802 8.02 6.93 252 hrs. Ex. 20
Compound-72 3.62 800 8.00 6.93 257 hrs. Ex. 21 Compound-77 3.63 838
8.38 7.25 230 hrs. Ex. 22 Compound-8 6 3.62 814 8.14 7.07 241 hrs.
Com. HTM-1 3.62 722 7.22 6.27 121 hrs. Ex. 1 Com. HTN-2 3.66 764
7.65 6.56 165 hrs. Ex. 2
[0163] In Table 3, when Examples 13 to 22 were compared with
Comparative Examples 1 and 2, while the organic EL devices of
Comparative Examples 1 and 2 had light emission efficiencies of
7.22 and 7.65 cd/A, respectively, when a current with a current
density of 10 mA/cm.sup.2 was passed therethrough, the organic EL
devices of Examples 13 to 22 had light emission efficiencies of
8.00 to 8.38 cd/A and therefore exhibited higher efficiency.
Moreover, with regard to power efficiency as well, while the
organic EL devices of Comparative Examples 1 and 2 had power
efficiencies of 6.27 and 6.56 lm/W, respectively, the organic EL
devices of Examples 13 to 22 had power efficiencies of 6.93 to 7.25
lm/W and therefore exhibited higher efficiency. Furthermore, with
regard to device lifespan (at a decay of 95%), while the organic EL
devices of Comparative Examples 1 and 2 had device lifespans of 121
and 165 hours, respectively, the organic EL devices of Examples 13
to 22 had device lifespans of 230 to 257 hours, from which it can
be seen that the device lifespan was increased.
[0164] It was found that, in each organic EL device of the present
invention, since the compound having a specific triarylamine
structure was chosen as the material of the electron blocking
layer, the carrier balance in the organic EL device was improved,
and therefore, higher light emission efficiency and a longer
lifespan were realized compared with a conventional organic EL
device.
[0165] The compound having a triarylamine structure of the present
invention can also be expected to achieve similar effects when used
as a constituent material of a hole injection layer, a hole
transport layer, or a light emitting layer.
INDUSTRIAL APPLICABILITY
[0166] An organic EL device of the present invention in which a
compound having a specific triarylamine structure is used has
increased light emission efficiency and also improved durability.
Therefore, the organic EL device of the present invention can be
applied to a wide variety of uses such as home electric appliances
and lighting equipment, for example.
LIST OF REFERENCE NUMERALS
[0167] 1 Glass Substrate [0168] 2 Anode [0169] 3 Hole Injection
Layer [0170] 4 Hole Transport Layer [0171] 5 Electron Blocking
Layer [0172] 6 Light Emitting Layer [0173] 7 Electron Transport
Layer [0174] 8 Electron Injection Layer [0175] 9 Cathode
* * * * *